The present invention relates generally to laser beam focusing devices used in laser welding systems, and more specifically to a high-power laser welding optical apparatus that includes a pressurized chamber and an aerodynamic window for preventing contaminants from damaging the internal components of the apparatus.
The advent of higher power, near-infrared (e.g., 1.07 um) lasers has rendered currently available optical systems used to focus laser light for welding purposes inadequate. Commercially available optical systems that are used with fiber-delivered laser beams typically demonstrate thermally-induced focal shift and focus quality degradation because the transmitting lenses and protective windows incorporated therein are subject to thermal distortion. This problem is exacerbated when any contamination (e.g., dust, soot, etc.) generated at the work surface contacts the delicate surfaces of the lenses. Fully reflective focusing optics provide a possible solution to this problem, but such optics usually require a transmitting “window” to protect the operative end of the laser delivery fiber. Such transmitting windows are known to be problematic because contaminants that accumulate on the window can impair the function of the laser beam focusing device and affect the quality of the final weld. Thus, there is an ongoing need for a laser beam focusing apparatus that does not suffer from these limitations.